1. Field of the Invention
The present invention relates to a conductive film, a display device having the same, and a method of evaluating the conductive film.
2. Description of the Related Art
Examples of conductive films, each of which is provided on a display unit of a display device (hereinafter referred to as a display), include a conductive film for a touch panel.
In such a conductive film, as shown in FIG. 23A, there is a demand for a technique relating to how to arrange peaks of the mesh pattern of the conductive film with respect to frequency peaks 120 of a black matrix (BM) of a display disposed in a square lattice shape in order to obtain a mesh pattern excellent in terms of visibility with respect to moiré. Moiré for the mesh pattern excellent in terms of visibility is defined to have a high frequency and a low intensity. Thus, there is a problem that it is necessary for a plurality of frequency peaks 120 of the black matrix of the display and a plurality of frequency peaks of the mesh pattern to be disposed such that distances between peaks are maximized. In order to solve the problem, various proposals have been provided (for example, refer to U.S. Patent App. No. 2013/0248239A1 (Corresponding JP2012-533887A) and JP2013-213858A).
U.S. Patent App. No. 2013/0248239A1 (Corresponding JP2012-533887A) discloses, as a conductive film, a conductor having a transparent substrate and an electrically conductive pattern. In the electrically conductive pattern, in 30% or more of the entire area of the transparent substrate, in a case where a straight line intersecting with the electrically, conductive pattern is drawn, a ratio (distance distribution ratio) of a standard deviation to an average value of distances between adjacent intersection points between the straight line and the electrically conductive pattern is equal to or greater than 2%. The electrically conductive pattern is a pattern with a borderline shape of figures forming a Voronoi diagram.
In such a manner, in U.S. Patent App. No. 2013/0248239A1 (Corresponding JP2012-533887A), it is possible not only to achieve excellent conductivity while not blocking eyesight but also to prevent a moiré phenomenon from occurring.
In contrast, JP2013-213858A relating to the application of the present applicants discloses a conductive film that has a transparent substrate and a conductive section having a mesh-shaped wiring pattern. The wiring pattern has the following characteristic. A sum of an intensity of moiré within a predetermined frequency range, in which a frequency of the moiré is determined depending on visual response characteristics, is equal to or less than a predetermined value, with respect to the frequency and the intensity of the moiré obtained by applying human visual response characteristics to frequency information and intensity information of the moiré. The frequency information and the intensity information are respectively calculated from peak frequencies and peak intensities of a two-dimensional Fourier spectrum of transmittance image data of the wiring pattern and peak frequencies and peak intensities of a two-dimensional Fourier spectrum of transmittance image data of the pixel array pattern.
In such a manner, in JP2013-213858A, it is possible to prevent moirés from occurring, and it is possible to greatly improve visibility.